“I would never fall in love if I was in a good relationship.” So says one participant in the women’s church group where Copenhagen-based wife and mother Kate (Kathrine Thorborg Johansen) confesses that she’s been having a three-year affair with another man, and doesn’t much regret it. It’s a line that sounds like sturdy, suitably Christian advice, but is it true? Kate’s husband Orla (Simon Sears) is attentive, attractive and empathetic; so is Andreas (Anders Danielsen Lie), the smart, offbeat archaeologist she’s smitten with at first sight. Alternately droll and emotionally acute, Maria Bäck’s “Brave New Love” never presents this romantic triangle as a problem with one solution; it’s considerably less judgmental than the church ladies as it gives its protagonist space to figure out if she really loves two people at once, or just loves nobody — herself included — quite enough.

Premiering in the main competition at Locarno, this is an emotionally intelligent, gently wry character drama of a distinctly Scandi stripe, occupying a comparable arthouse lane to Dag Johan Haugerud’s Oslo Trilogy and recent works by Joachim Trier, albeit with a distinctly feminine point of view behind the camera. It’s not just Danielsen Lie’s reliably interesting presence that brings to mind “The Worst Person in the World” at points, as Bäck’s script (on which Trier collaborator Eskil Vogt was a consultant) ponders similar feelings of middle-class millennial female unrest in a character who simply opted for marriage and family earlier in life. Relatable and discussable, Bäck’s second narrative feature likely reps an easier sell to international distributors than her first, the darkly heightened psychodrama “Psychosis in Stockholm.”

It’s on a camping trip with her family that Kate first locks eyes with Andreas — they’re both stark naked, having just swum in the same forest lake, but that’s rendered almost incidental by the telling intensity of their shared gaze. When he walks off, Kate scribbles down her number and leaves it under his towel. But then “Brave New Love” takes the first of several swerves: Instead of charting its protagonist’s first steps into infidelity, it skips breezily through snapshots from the ensuing years-long affair. Andreas becomes almost as entrenched a partner in her life as her husband, though she manages to keep the relationships strictly separate — a rationalized arrangement in her mind, though that collapses when Andreas calmly announces that he’s moving to Greece for a job.

It’s only with the affair on ice that disorder creeps into Kate’s life, while Orla and their teenage daughter Athena (an excellent Noemi Carbone Mannov) begin to sense something amiss. Editor Julius Krebs Damsbo artfully toggles between present and past, gradually filling in the sensual specifics of the affair — which aren’t entirely as you’d expect — while tracking Kate’s spiraling sense of mourning for whatever it was they had. Without it, her comfortable marriage to Orla seems that much more confined, the increasingly separate islands they seem to be on underlined by DP Maria Von Hausswolff in one tense bedtime argument scene, with the couple’s faces visible only in their respective bathroom-vanity mirrors. Kate seeks solidarity in the aforementioned church group, despite not being much of a believer herself; she doesn’t quite find it, but the candor enabled by all-female company is its own kind of liberation.

Thorborg Johansen’s subtly nervy performance articulates Kate’s antsy anxieties and erratic moods without making her too much of a scatty romantic heroine. She’s believable while not straining too hard for our sympathy, which winds up fairly evenly divided between all the principals anyway — with a slight advantage to Sears’ beautifully modulated turn as Orla, battling his own emotional and bodily securities while trying to hold down the fort. Handed the most script’s least knowable character, Andersen Lie nonetheless sharply gestures to a life outside his relations with Kate, something she herself hasn’t much considered. In its efforts to be fair to all these characters — via a key, spirit-lightening change of scene — “Brave New Love’s” final act winds up a little fuzzy, though that’s a preferable flaw to tunnel vision: Bäck’s film prefers untidy personal drama to a tidy moral verdict.